This invention relates to a pick and place mechanism for picking an object and placing the same on an intended position, and more particularly, to a pick and place mechanism for picking a micro contactor, changing the orientation of the contactor and placing the contactor on a substrate to mount the contactor thereon. Typically, the micro contactor in this invention is used in a probe card to test semiconductor wafers, semiconductor chips, packaged semiconductor devices or printed circuit boards and the like with an improved frequency bandwidth, pin pitch and contact performance and reliability.
In testing high density and high speed electrical devices such as LSI and VLSI circuits, high performance contact structures, such as probe contactors or test contactors, must be used.
The inventors of this invention has introduced a unique contact structure in the U.S. Pat. No. 5,989,994. This invention is directed to a pick and place apparatus and method to be used in forming the contact structure shown in the patent application. This invention is also directed to a production process for producing the contact structure in a manner suitable for the operation of the pick and place apparatus of the present invention. The contact structure disclosed in the present invention is similar to that shown in the above noted U.S. Pat. No. 5,989,994, but has small differences therefrom.
In the application of semiconductor testing, circuit testing, or the like, the contactors produced through a microfabrication process must be mounted on a substrate such as a probe card to form a contact structure. However, because the size of the contactors is very small, it is not possible to manually handle the contactors in such an assembly process. Thus, there is a need of a pick and place mechanism for handling such small sized contactors for picking, changing the orientation, and placing the contactor on the substrate for bonding.
Therefore, it is an object of the present invention to provide a pick and place mechanism for handling the micro contactors for mounting the micro contactors on a substrate to form a contact structure.
It is another object of the present invention to provide a pick and place mechanism for picking, changing orientation, and placing the contactor to form a contact structure.
It is a further object of the present invention to provide a contact structure having a large number of micro contactors where each of the contactors has a triangle base to be attached to the substrate of the contact structure.
It is a further object of the present invention to provide a production process for producing micro contactors, each having a triangle base to be attached to a surface of the substrate forming the contact structure with use of a pick and place mechanism.
In the present invention, a contact structure for establishing an electrical connection with a contact target is formed with a substrate of a planar surface on which a plurality of contactors produced by a microfabrication process are mounted. In the present invention, the pick and place mechanism is utilized to assemble the contactors on the substrate by picking from an intermediate plate, changing orientations, placing the contactors on the substrate and bonding the contactors to the substrate.
The contact structure of the present invention has a contact substrate on which a plurality of contactors are mounted. Each of the contactors has a beam like shape formed through a semiconductor production process. The contactor is comprised of a silicon base having an inclined support portion created through an anisotropic etching process, an insulation layer formed on the silicon base and projected from the inclined support, and a conductive layer made of conductive material formed on the insulation layer so that a beam portion is created by the insulation layer and the conductive layer, wherein the beam portion exhibits a spring force when the tip of the beam portion is pressed against a contact target.
Another aspect of the present invention is a pick and place mechanism for assembling a large number of contactors on the contact substrate. The pick and place mechanism includes a first area for positioning an intermediate plate having a plurality of contactors thereon, a second area for positioning the contact substrate for receiving the contactors thereon, a carrier provided between the first and second areas for converting a direction of the contactor to a predetermined direction when receiving the contactor on a seat, a first transfer mechanism for picking the contactor from the intermediate plate and placing the contactor on the seat of the carrier, a second transfer mechanism for picking the contactor from the seat of the carrier while maintaining the predetermined direction of the contactor defined by the carrier and placing the contactor on the contact substrate for bonding.
A further aspect of the present invention is a process for producing the contact structures having a contact substrate on which a plurality of contactors are mounted. The method of producing the contact structure is comprised of the steps of providing a silicon substrate cut in a (100) crystal plane, forming a boron doped layer on a surface of the silicon substrate, forming a first insulation layer on the boron doped layer, forming a second insulation layer on a bottom surface of the silicon substrate, forming an etch window in the second insulation layer, performing an anisotropic etch through the etch window, and forming a conductive layer on the insulation layer, applying an intermediate plate under the silicon substrate so that a contactor produced in the foregoing process is transferred to the intermediate plate, picking the contactor from the intermediate plate and changing a direction of the contactor to a predetermined direction, and placing the contactor on the contact substrate with the predetermined direction and bonding the contactor to the contact substrate.
According to the present invention, the contact structure has a very high frequency bandwidth to meet the test requirements in the next generation semiconductor technology. Since the contact structure is formed by assembling the contactors on the substrate with the pick and place mechanism of the present invention, a large number of contactors can be aligned in a small space and in a predetermined direction, which is suitable for testing a large number of semiconductor devices at the same time.
Since the large number of contactors are produced at the same time on the substrate with the use of the microfabrication technology without involving manual handling, it is possible to achieve consistent quality, high reliability and long life in the contact performance. Further, because the probe contactors can be fabricated on the same substrate material as that of the device under test, it is possible to compensate the temperature expansion coefficient of the device under test, which is able to avoid positional errors.